Withdrawal of southwest monsoon seemed to have acquired a sense of urgency with more areas emerging out of its influence on Monday.

This has reduced humidity levels but caused day temperatures to rise over many parts of northwest, east and central India.

An India Meteorological Department (IMD) update said that the monsoon has withdrawn from Uttarakhand, Uttar Pradesh, Rajasthan, Gujarat, entire Madhya Pradesh and many parts of Bihar, Jharkhand, Chhattisgarh and Maharashtra.

WITHDRAWAL LINE

The withdrawal line passed through Forbesganj, Ranchi, Raigarh, Yeotmal, Ahmednagar and Alibag on Monday.

Conditions are favourable for further withdrawal from the remaining parts of east and northeast India during the next three days.

A short-term outlook for October 15 to 17 said that the weather is likely to be mainly dry over most parts of the country outside south peninsular India where isolated to scattered rain or thundershowers is likely during the next four days.

The IMD expected no heavy rainfall at any part of the country during the next five days.

The maximum and minimum temperatures are likely to fall gradually by about 2 degrees Celsius during the next five days.

Satellite imagery on Monday showed convective clouds over parts of southeast Bay of Bengal and the Andaman Sea.

These seas are predicted to be in a state of flux through the course of the week, according to international models.

THUNDERSHOWERS

The Chennai Met Centre said in its update that rainfall occurred at a few places over interior Karnataka during the 24 hours ending Monday morning. Isolated rainfall occurred over Tamil Nadu, Andhra Pradesh, Kerala and coastal Karnataka.

Forecast for the next two days said that rain or thundershowers are likely at a few places over Tamil Nadu, Puducherry and Kerala.

Isolated rain or thundershowers have been forecast over Karnataka, Lakshadweep and Andhra Pradesh.

The European Centre for Medium-Range Weather Forecasts (ECMWF) maintained the outlook for the nearly contiguous water bodies of west Pacific/South China Sea/Bay of Bengal to rhyme in unison beyond October 15 precipitating onset of northeast monsoon (winter or reverse monsoon).

The trough encompassing these seas held into place on Monday mostly by a re-energised tropical storm Parma is expected to hold as such even after Parma weakens after an expected landfall over south China.

In fact, international models showed at least two fresh areas of convergence to the southeast of the Philippines on Monday, one of which would go on to become another typhoon-in-the-making, the ECMWF outlook suggested.

This likely typhoon is predicted to make an eventful landfall over the Philippines around October 22 according to the ECMWF outlook available on Monday.

After weakening, the westward-tracking typhoon would still likely have a ripple effect on the Bay of Bengal downstream.

Indian farmers had been praying for rain after the weakest monsoon season in 40 years had left their crops stricken by drought. But when the rains finally came, forceful and incessant at six times their normal levels, they left behind the worst floods southern India had seen in more than a century.

Weather officials blamed the heavy rains in Karnataka and Andhra Pradesh on a low-pressure system over the Bay of Bengal. So far, over 250 people have died in flooding made worse when officials were forced to open dams for fear they might burst. Some 1,500 relief camps have been set up for the estimated 2.5 million people who were displaced as the raging water destroyed entire villages, washing away roads, bridges, crops and livestock. (See pictures of India's 2008 floods.)

Although flooding has recently become commonplace in India - in 2008, over 3 million people were displaced when the Kosi river in Bihar burst its banks - but this year's deluge came as a shock because if followed a protracted drought, and a monsoon season branded a dud by the authorities. To experts who've tracked the effects of climate change, however, the flooding came as no surprise. In its fourth assessment report in 2007, the Inter- Government Panel on Climate Change (IPCC) predicted that more extreme droughts, floods, and storms, would become commonplace in the future, and that these intense weather conditions would follow in close succession to each other, often in the same areas.

The volatile weather patterns predicted by the IPCC are already beginning to show in India. The Doni river, a 93-mile stretch of water in north Karnataka has come to be known as "the Yellow River of Bijapur," after China's Hwang Ho. While the Chinese river is infamous for its sudden changes in course, the Indian version, whose water many consider no longer fit for human consumption, is gaining notoriety for its unpredictable nature - flash floods one day, barely a trickle the next. "We need to find a way of storing the excess water and using it through the rest of the year," says A.K. Bajaj, Chairman of India's Central Water Commission. (Read "India's Floods: a Manmade Disaster?")

The IPCC's predictions are grim for a country that still hasn't figured out an effective strategy for water management. In the northwest alone, the water table is falling by about 1.6 inches per year, according to the GRACE (Gravity Recovery and Climate Experiment) mission. At least half of India's precipitation comes from the annual monsoon rains, and as they become increasingly diminished and unpredictable, the country faces an imminent threat of extreme water shortages. Changing rainfall patterns aren't the only climate- change effect threatening India's water supply: Himalayan glaciers - the source for the many Indian rivers such as the Ganges - are melting at a rapid rate as a result of warmer temperatures. (See TIME's photo-essay "Worst Floods in 50 Years Hit Manila.)

Meager monsoons mean meager crops, and meager income, for Indian farmers. This year alone, the loss to crop yields and property in the two states has totaled almost $7 million. Dr. William Cline, a senior fellow at the Center for Global Development (CGD) and the Peterson Institute for International Economics says that of all the potential damage that could occur from climate change, damage to agriculture is likely to be the most devastating. "In the southern parts of India, damage will be substantial and similar to that in other countries also located close to the equator," he says. "In these locations, where temperatures are already at high levels, an increase in temperature will surpass crop tolerance levels."

Already, food shortages have become a major concern for the government, as the retail prices of vegetables shoot up. Damage to the onion crop in the recent floods, for example, saw the vegetable's price double within days.

Even without factoring in climate change, India's got a plate full of problems to deal with. Officials say ineffective management, bureaucracy and disaster planning have all contributed to the worsening of an already bad situation.

Carbon dioxide levels climbing toward a doubling of the 280 parts per million (ppm) concentration found in the preindustrial atmosphere pose the question: What impact will this increased greenhouse gas load have on the climate? If relatively small changes in CO2 levels have big effects-meaning that we live in a more sensitive climate system-the planet could warm by as much as 6 degrees Celsius on average with attendant results such as changed weather patterns and sea-level rise. A less sensitive climate system would mean average warming of less than 2 degrees C and, therefore, fewer ramifications from global warming.

Human civilization is now running an experiment (and without a control) that will definitively determine the answer. Scientists, however, have also realized that history can be a guide: Two new papers published in Science this week examine the historical record preserved in a stalagmite and microscopic seashells, respectively, to offer some clues.

Earth scientist Aradhna Tripati of the University of California, Los Angeles's Department of Earth and Space Sciences and her colleagues extracted a record of past atmospheric concentrations of CO2 stretching back 20 million years from the shells of tiny creatures known as foraminifera buried in a column of ocean mud and rock. The microscopic animals build shells of calcium carbonate out of minerals in seawater-a process that is affected by the water's relative pH (acidity), which is, in turn controlled by the level of CO2 in the atmosphere. More CO2 in the atmosphere means a more acidic ocean.

"The two species we picked to analyze [Globigerinoides ruber and G. sacculifer] are both ones that are around today, and the living animals actually have photosynthetic algae as symbionts, which means that they live in the surface ocean, since the algae require sunlight to survive," Tripati explains. And that means the fossil record of their shells will reveal the relative acidity of the surface waters in the ratio of boron to calcium as well as the specific chemical signature of the boron itself. "When seawater is more acidic, less boron gets incorporated into the calcium carbonate shells," she adds.

The researchers first matched this fossil record secured by the Integrated Ocean Drilling Program Expedition in the western tropical Pacific to existing records from bubbles trapped in Antarctic ice cores that stretch back 800,000 years, which preserve a precise record of past atmospheric composition. Thus reassured of the technique's accuracy, they plunged back into deep geologic time.

"Modern-day levels of carbon dioxide were last reached about 15 million years ago," Tripati says, when sea levels were at least 25 meters higher and temperatures were at least 3 degrees C warmer on average. "During the middle Miocene, an [epoch] in Earth's history when carbon dioxide levels were sustained at values similar to what they are today [330 to 500 ppm], the planet was much warmer, sea level was higher, there was substantially less ice at the poles, and the distribution of rainfall was very different."

Further, "at no time in the last 20 million years have levels of carbon dioxide increased as rapidly as at present," Tripati adds; CO2 concentrations have climbed from 280 ppm to 387 ppm in the past 200 years. And "our work indicates that moderate changes in carbon dioxide levels of 100 to 200 parts per million were associated with major climate transitions and large changes in temperature"-indicative of a very sensitive climate.

A nearly 400,000-year record of Ice Age transitions preserved in a stalagmite in the Sanbao and Linzhu caves of Hubei Province in China would seem to offer evidence in support of the sensitive climate scenario. The stalagmites, composed of calcium carbonate leached from dripping water, preserve a record of monsoon rainfall in the region by their composition. Paleoclimatologist Hai Cheng of the University of Minnesota and his colleagues then compared this record with climatic transitions, such as the shift into and out of an Ice Age.

The rock record reveals that such rainfall changes occur at the same time as general alterations in the relative strength of sunlight hitting the planet thanks to periodic shifts in Earth's orbit, known as Milankovitch cycles. At the same time as the solar heat increases, according to the monsoon record published in Science, CO2 levels also begin to rise.

"Climate systems are well linked worldwide, such as sea-level, CO2, ice sheet[s], the Asian monsoon, regional temperature and precipitation," Cheng says. "So a change in one of them could trigger changes in others." And that might mean the climate is too sensitive to tolerate current levels of CO2 without changing the conditions that have allowed human civilization to flourish in the past 10,000 years.

The world is going toget hungrier this century, and on a scale that will make the famines of the 1980s look paltry. The maths are simple and devastating: in 40 years' time the global population will be 9.2 billion people - a third larger than it is now. But to feed us all, the UN Food and Agriculture Organization says, we will need to produce twice as much food.

That's because, despite the threats of this century, most developing countries will get richer. At present 350m households in the world live on £8,000 a year or more. That figure is projected to increase to 2.1bn by 2030. And the richer they are, the more wastefully people eat. Generally the poor eat vegetables, while the rich eat food that eats vegetables. Lots of it. To produce 1kg of beef takes 10kg of grass or soya-based feed. A farmed fish will have eaten three times its weight in wild fish. And the rate at which the richest consume these things is amazing: Americans consume 120kg of meat each per year; in the developing world they eat 28kg.

If the world develops as economists predict, it is hard to see how we can possibly meet these demands: environmentalists like to say that the 2050 population would require the resources of two earths to sustain it. No wonder the British government's chief scientific adviser John Beddington says: "Food security represents a greater threat to mankind than climate change itself."

There lies the other big problem. While we look for ways to produce that extra food, the rapidly changing climate is going to make the earth a less efficient piece of farmland. Large swaths of the tropics and the equatorial regions will get hotter and drier, and while that won't leave them unable to grow things, what they can grow will change radically. The 2°C increase in average temperatures that is accepted as the likely minimum this century is enough to cause major shifts in the seasons and in what crops work where.

The great irony of this change is that, initially at least, most of us in the richer parts of the world will benefit. It's in the tropics, where most of the world's poor live, that climate change is damaging agriculture, and will continue to do so. Essentially, the belt round the centre of the earth will get hotter and drier, while those of us who live in the north of the northern hemisphere will see more warmth but also more rain. This will extend our growing seasons and increase the geographical area where it's possible to grow crops. Canada and Russia are among the countries expected to do well, as are northern China and northern Europe. But the Mediterranean countries, southern American states and California don't look comfortable at all. Spain, for one, is painted a nasty red on all the maps showing where water will be short come 2050.

And in Britain? "Winters are going to get warmer and wetter - summers much warmer and dryer," says Robert Watson, chief scientist at the Department for the Environment, Food and Rural Affairs. This will certainly mean that we can grow more, especially some of the food such as salad vegetables and fruit that currently we largely import. Already British farmers are experimenting with apricots, peaches, almonds and olives; in the future, staple crops such as durum wheat, soya and maize might become viable, too.

But we should not get too seduced by the vision of a new Britain with all the abundance of the Mediterranean nations: we are certain to be affected in our turn by the global shortages caused by the agricultural collapses in the tropics. Britain imports half its food, and we are predicted to see our population increase by 10 million. The failure of the monsoon in India this summer is already pushing up global food commodity prices such as those of wheat, sugar and rice. And we are likely to see other less pleasant effects in Britain: floods, storms and heatwaves will become more common. Defra predicts average summer temperatures in southern England will be up to 8°C higher than they are now.

This is why the British government has suddenly started making worried noises about British "food security". While it's hard to imagine Britain going hungry, we are certain to see food prices rise, and we may find that the cheap meat we've come to expect for so long reverts to being the sort of luxury it used to be. If Britain had to grow all its own food, it's said, we could do it - but at an immense price: it would mean an end to any wild or forested land in the parts of the country where farming is possible.

But this is nothing compared with the changes that are happening or imminent in the tropical world. Rice production, the staple food of most of Asia, is already moving northwards, forcing millions of people to change ways of living that have sustained them for centuries. Along the coastal fringes of Asia, people's lives are changing radically, as a huge increase in storms coupled with a rise in sea levels (which is now predicted to be a metre this century) brings salt to their fields and makes growing rice impossible.

Half of the poorest billion people in the world live in South Asia, as do many of the 5 million children who die every year of diseases caused or exacerbated by malnutrition. According to a report by the Asian Development Bank, 1.6 billion south Asians will find their food security at risk because of climate change.

In Africa and parts of Latin America predictions are just as hair-raising. Maize is one of the world's four most important food crops and the staple of more than a quarter of a billion east Africans. It's a hugely important food for animals as well. Maize is vulnerable to water problems and to temperature changes. As Andy Jarvis, an award-winning crop scientist, puts it: "When you look at the graph, under even small average heat rises, the line for maize just goes straight down." It's estimated that maize production will drop in sub-Saharan Africa and much of India by 15% in the next 10 years alone. By 2080, according to government scientists in South Africa, the region can expect to see a 50% drop in crops of all the cereals.

Among the luxuries of living in our comfy corner of the world, is the fact that climate change still seems to be a problem of the future, something that we need to worry about less for ourselves than our grandchildren. But for many millions of people the devastation caused by changing seasonal patterns and unpredictable weather is already a clear and present danger. First-person accounts collected by Oxfam from agricultural workers around the world all say the same. Whether they're in the east African savannahs, the Peruvian altiplano or the fertile coastal wetlands of Indonesia, all complain that the seasons have become less certain, rainfall unpredictable and that their crops or their animals have suffered. There are new pests and diseases.

While it is still not possible to say with certainty that this is caused by human beings burning fossil fuels, it is undeniable that catastrophic changes are going on in the climate system. Filter the news with a climate change alert for a few months, and you watch a stream of worrying official statistics trickle in - all of them bad news. The southern Indian state of Karnataka reports a drop in rainfall of 6-8% since 1990. Tanzania and other east African countries report already an average warming of 1.5°C since 1990. Chinese meteorologists say that parts of their country have experienced the same. These figures may not seem enormous, but their effect is dramatic. According to the research of the IPCC, the Intergovernmental Panel on Climate Change, just half a degree of average temperature increase will reduce the yield of India's wheat crop by 20%. And India is the world's second largest producer of wheat.

Where's the good news? Well, there is still enough land to feed us all. Overall, less than 60% of the world's agricultural potential is exploited. If we act now to help countries adapt and prepare for the changes that are coming, it's possible that some of the most distressing effects - mass migration, conflict, starvation on a huge scale - could be diminished. There is a model. The world population quadrupled during the 20th century, and agriculture faced up to the challenge: global food production doubled between 1950 and 1980, in the so-called green revolution.

That increase happened primarily through the use of artificial fertiliser in countries such as India and China. And in technology lie many hopes. Even today African farmers use less than 1% of the fertiliser that we use in the rich world. A recent programme of government subsidy for new seeds and fertiliser in Malawi raised the maize yield in that famine-prone country from an average 1.2 tonnes a hectare to as much as 4 tonnes. (In Iowa in the US, the average rain-fed maize yield is 10 tonnes per hectare.) Genetically modified crops may provide some answers, and already there are efforts to produce new crop strains for the new world: maize that will tolerate less water and more heat, rice that can put up with a saltier soil.

But there may be more traction in less hi-tech solutions. Clearly, encouraging billions of poor world farmers to buy fossil-fuel-based fertiliser is no more sustainable than burning all the oil. There are many voices arguing that the only sensible way to increase food production is through organic and sustainable measures. While water is generally agreed to be one of the most potent sources of conflict in this coming century, we still use it very badly. Only 17% of all the world's agricultural land is irrigated.

In Africa, according to a World Bank study, rainwater-fed farms lose $27 (£17) with every 1°C rise in temperature this could be equivalent to a month's profit for the average poor farmer; but irrigated farms gain $35. "Micro-harvesting" of rainwater and other low-tech irrigation ideas could make enormous differences, but these require education and investment. "We need to reinvent our agriculture," says Oxfam India's Shaik Anwar. "We must rebuild the forest areas, conserve water, make agriculture more organic and sustainable. At the moment we are losing our groundwater very quickly, destroying soil nutrients, and farmers are going into debt because they are dependent on fertiliser and other inputs."

Hi- or low-tech, these efforts will need funding by the rich world. It is estimated that we need to spend $50bn a year helping the poor world adapt to climate change - a sum that Oxfam and other international agencies will be asking the UN states to commit to at December's summit in Copenhagen. The need is urgent - climate-change-related disaster is already a reality across much of the tropics. "If there is 2°C of warming, I cannot imagine what will happen to us in southern India," says Shaik Anwar. "The impact will be huge on water, on people's ability to work, on nutrition, on animals. Four out of five families in rural Andhra Pradesh are already living on the threshold of disaster."

We have both a practical and a moral reason to help. The first is simple: if crops fail in India we will feel the effects very quickly - the enormous price rises in staple foods in Europe in early 2008 were born in the great cereal lands of Brazil and India and in the rice paddies of south and east Asia. A poor crop there, a panic in the commodities markets, and suddenly British shoppers found their weekly food bills were up 10-15%. Some of us even had to forsake Sainsbury's for Lidl. In poorer countries, it thrust people back into poverty. I've met farming families in Cambodia and India where the parents died - from hunger, or by their own hands because they were too ashamed to go on.

The moral reason? We burnt the fossil fuels in our own drive for development - and thus got the planet into its current mess. And we're still doing it. Though India is industrialising fast, in the rich world we still produce 10 times as much carbon per head as Indians do. Peter Balaram, project director of Apps, the NGO trying to help in Anantapur, says: "Climate change is everyone's responsibility, but especially that of the industrialised nations. My plea is for richer countries that are more responsible to come to the rescue of countries on the edge." AR

Alex Renton's report for Oxfam International on the impacts of climate change on humans, Suffering the Science, can be downloaded atwww.oxfam.org.uk/policy/